The invention concerns a winder for winding a running web of paper, foil and the like. Also called "Pope Rollers," such winders form generally the end section of a paper machine, imparting a roll shape to the paper web accruing there. They are also used to rewind an already finished roll so as to create a new roll.
In either case, the roll is to have very specific properties, specifically with regard to the winding hardness. Beginning with a certain initial value, the winding hardness is supposed to drop to an end value. The drop should be maximally uniform from the first to the last lap. It is to have a certain gradient, i.e., not too severe and not too weak. The pattern of winding hardness should at any rate not have points of abrupt change, for instance a sudden drop.
All of this has been sought heretofore but not accomplished. Instead, winders of prior design produce rolls where the core is extremely hard. As a result, this core is unusable because the web is overstretched in this region and breaks, so that this part needs to be discarded as scrap.
Prior means for influencing the winding hardness are two measures used, e.g., on rotary slitters. One is constituted by subjecting the web in winding to a more or less heavy tension. The other measure is forcing the roll more or less heavily on the support roll, for instance by application of pressure on the axles of the winding drum, or by contact with a rider roll which is arranged parallel to the roll being created and is forced onto it creating a line pressure between the paper roll and the support roll.
A line pressure is frequently created in the said primary section, by the weight of the winding drum, between the paper roll being created and the support roll. The winding drum is extremely heavy, reaching a dead weight of several tons, so that an appropriately high line pressure is created. The latter is responsible for the extremely high winding hardness of the core of the paper roll.
Providing a drive of its own for the winding drum, i.e., a so-called center drive, is advantageous because it allows managing the winding hardness still the best. In this arrangement, the said slide (or slide pair) including the guideways is mounted on a swivel arm, so that the slide performs the same swivel movement as the primary levers.
Since the paper roll grows as it passes the primary section, i.e., its diameter increases, also the radial distance between the drive and the axis of the support roll must be enlarged at the same ratio. Serving this purpose is the adjustment of the radial position (tracking) of the slide. The tracking has so far been realized by means of a hydraulic control where the distance between the drive slide and the winding drum is continuously measured while passing through the primary section, and the slide tracking is accomplished by means of two hydraulic cylinders. Such a control is expensive. As a further aggravation, the weight of motor and gear set needs to be compensated for.
The problem underlying the invention is giving the radial adjustment, or tracking, of the slide a design such that it will be simple in structure, that also certain tolerances may be allowed regarding the control accuracy, and that it will work reliably.